There are television receivers which provide a multi-screen view, e.g., a double-screen view comprising a main screen view on one side of a display and a sub-screen view of almost the same size on the other side of the display.
An example of such a conventional television receiver will be described hereinafter, in reference to FIGS. 5 and 6.
As shown in FIG. 5, such a television receiver has two tuners 21 and 22 respectively selecting pictures from desired channel broadcast TV signals, under a control of a controller 29. These first and second tuners 21 and 22 each have a picture signal processing unit for converting the received TV signal into an intermediate frequency (IF) picture signal.
These IF picture signals are combined into a double-screen view signal in a multi-screen processor 26 and then applied to a display 28 such as a CRT. Thus, the display 28 provides a double-screen view comprising a main screen view based on the first picture signal on one side of a display and a sub-screen view based on the second picture signal on the other side of the display at almost the same sizes.
In the double-screen view mode, the first and second picture signals from the first and second tuners 21 and 22 are compressed in the horizontal direction by a factor of two by a main picture compressor 24 and a sub-picture compressor 25, respectively, so that their horizontal sizes are reduced by 1/2. Then the compressed picture signals from the main picture compressor 24 and the sub-picture compressor 25 are combined in the multi-screen processor 26. The combined picture signal is then supplied to the display 28. At this time, a switch SW5 is controlled by a controller 29 so as to establish a signal path M to provide a double-screen view signal from the multi-screen processor 26 to the display 28.
Further, a direct signal path N is provided for supplying the first picture signal from the first tuner 21 to the display 28 in a bypassing manner over the circuit units 24, 26 etc. Thus, the direct signal path N is established under a control of a controller 29, the conventional single-screen view responding to only the first picture signal is displayed on the display 28 through the direct signal path N.
Therefore, in the double-screen view mode, the first picture signal selected by the first tuner 21 can be displayed through the main screen X and the pictures selected by the other tuner can be displayed on the sub-screen Y as shown in FIG. 6, while in the single-screen mode, the pictures selected by the first tuner 21 can be displayed on the single-screen.
Among such television receivers described above, there are some receivers that have been designed to display pictures on the main screen and the pictures received from other broadcasting stations on the sub-screen as reduced-size pictures so as to give convenience to users in selecting channels. Such a function is called the channel-search function and has been added to double-screen television receivers as a new function in these years because this function facilitates the channel-search while displaying multi-window view (hereinafter, referred to as the search-screen) as shown in the figure.
In a pending Japanese patent application (Tokugan Hei) No. 7-30880, assigned to the same applicant of the present patent application, a television receiver for displaying multi-window view on a sub-screen is proposed. In the co-pending application, it is also proposed that a channel-search operation for selecting a desired broadcast TV signal is carried out on a multi-window view provided on the sub-screen of the display by locating a cursor on a desired channel picture in one of the multiple windows.
The channel-search technique proposed in the Japanese application is advantageous because it continuously displays the current picture on the main screen while searching for a desired channel picture on the sub-screen. However, the proposed technique has a problem that after the completion of the channel-search operation, the display the screen mode just before the channel-search operation is lost. Thus, the user is required to manually reset the screen mode on the display.
Television receivers as proposed in the pending application, as well as conventional television receivers have a problem that users are required to manually reset the current display to a desired channel display.